Refrigeration compressor



Mach 3, 1942. TQUBORG Y 2,274,943

REFRIGERATION COMPRESSOR Filed lay 2, 1940 2 Sheets-Sheet 1 83 36a refs INVENTOR Jns Ta/borg ATTORNEY March 3, 1942.`

J. TUBORG 2,274,943

REFRIGERAT ION C OMPRE S SOR Filed May 2, 1940 2 Sheets-Sheet 2 INVENTOR Jensv Touoly ATTORNEY Patented Maas, 1942 UNITED VSTATES PATENT oFFicE .Jens Touborg, Tecumseh, Mich.`

Application May 2, 1940, Serial No. 332,973

4 Claims.

This invention relates to refrigeration compressors, particularly to the enclosed type known as hermetic compressors, and it is directed to the provision of improved means for making' and operating such compressors, particularlyl with respect to a novel main shaft construction including pumping elements to supply lubricant to the shaft bearings and piston.

A common and well known form of hermetic compressor includes an overhead electric motor whose shaft is coupled to the connecting rod of a reciprocating compressor, all enclosed in a casing, and wherein lubricating oil is contained in the lower portion of the casing for supply to the working parts. In my prior patent, No.

2,146,097, of February 7, 1939,.I have disclosed such general form, utilizing a cast shell for housing and mounting the motorand compressor, and providing the motor shaft with a dependent portion adapted tovbe connected to the connecting rod of the compressor piston.

In the above mentioned patent. I endeavored to provide for a supply of lubricating oil to the main bearing, by drilling the crank with a diagonal hole extending from the. oil body to the main sleeve bearing, it beingconsidered that in such a diagonal passage, every point therein would be a centrifugal pump which would lift the oil to the bearing. I moreover provided for substantial immersion of the crank portion ini the oil bath, so that the piston would be lubricated by immersion and splashing.

Practical experience with thestructure disclosed in that patent, as just referred to, has

shown that, amongother things, two unsatisfaci tory conditions are enco'untered.l First, the drilling of a diagonal duct through a, steel shaft, even when modern precision tools and methods4 are employed, is a. difficult operation, and a significant percentage of the shafts arespoiled due to inaccurate drilling, and -must therefore be rejected with attendant economic loss.

Second, in actual operatiom it has been' discovered that the highly volatile refrigerant,

which always gets mixed into the oil either by solution or mechanical entrainment, will tend to separate in the diagonal passage. `The reason for this becomes apparent upon analysis. It is vpractically impossible to submerge the passage entirely, and there is therefore a portion of it that acts centrifugally, labove the oil bath. This centrifugal action causes theoil and inciudad refrigerant to separate, thereby creating globules of low density vapor in the impeller,

Since the centrifugal is linherently ineffective as a pump for vapor, the gas simply blocks the diagonal passage, and causes a vapor lock condition which interferesV with the intended function of the pump. Lubrication of the main thereby diminished.

According to the present invention, I have devised an overhead motor type of compressor, with-a substantially reduced depth for the oil body in the base of the casing, and with elimination of opporunity for vapor lock formations in that portion of the pumping mechanism which operates centrifugally. This I accomplish by means of a different form of shaft and pump, with associated bearing structure. As the present description proceeds, it will moreover be apparent that simplified machine operations may be utilized, thus curtailing spoilage losses, as well as providing for greater efiiciency of operation.

In one aspect of this invention, I provide ay lmain shaft having two spaced concentric porpoints towhichthe oil is to be taken. By providing spaced concentric shaft portions, as just described, and by forming the connecting rod crank at a mid portion of the shaft, I am moreover able to provide for positive feed of oil to the wrist pin, as well as the main bearing, and to two-stage or boost the oil pressure for this important delivery point.

In further explanation of the principle just enounced, it may here be added that I provide a shaft structure wherein the eccentric is offset' from, or lies beyond, the trace of the concentric shaft sections. If a vertical riser from the submerged centrifugal be taken along the shaft to this eccentric portion, then the eccentric itself may be formed with a second centrifugal impeller, constantly supplied or primed by the first, and thereby producing an effluent Whose effective l head is much greater than that obtainable by utilizingeither the concentric shaft section, or a dependent offset section, alone. 'I'he oil delivered in this fashionmay in turn be led fto the wrist pin through suitablev connecting ducts.

bearing is Associatedwith ysuch eccentric shaft portion is another portion between the concentric shaft sections, in which a counterweight may be positioned in a novel manner. This feature, in turn, is related to the general assembly of the compressor which, inv this case, comprises a sheet metal housing and an included compressor casting, the latter being formed with an open portion for facilitating the insertion of the novel shaft structure and its assembly with the related parts.

Another related feature concerns` itself with the bearing for the lower concentric shaft portion, which is so devised as to admit oil to the submerged -centrifugal pump, and withal close certain passages which are formed as an incident of the manufacturing operations.. This feature not only aids to curtail manufacturing costs, but also reducestendencles toward vibration and wear, as the compressor is operated.

It may be noted that the invention as herein presented contains subject matter in common with my copending application Serial No. 327,063,

flied March 30, 1940, wherein emphasis is laid l upon a novel means forfeliminating knock from the head end of the compressor under certain.

operating conditions. While such means may be used conjointly with the subject matter herein claimed, it will of course be understood that the present invention may also be used independently thereof, andaccordingly is presented in this application. The invention may be more clearly understood by reference to the following description, read in connection with the accompanying drawings,

wherein:

Fig. 1 is a view, partially in side elevation and partially in section, of the assembled compres- SOT:

Fig. 2 is an enlarged section through the compressor body showing particularly the shaft, bearing, and oil pump formation;

Fig. 3 is a. section through the crankshaft, taken on the line V3--3 of Fig. 2;

Fig. 4 is a section, on a slightly reduced scale, on the line 4--4 of Fig. 2; and

Fig. 5 is a fragmentary section, on the scale of Fig. 1, showing a modification for the pump riser.

Referring first to Fig. 1 for a general description. there is shown a casting body In including a compressor which is operated by a driving motor Il disposed above the compressor, both of which are wholly enclosed by a casing consisting of two ,abutting sheet metal shells l2 and i3. Each shell is formed on its open end witha flange, I2a and I3a respectively, which are welded to each other after the other parts have been properly assembled. The upper shell I2 is formed with a cylindrical portion I6 mergl ing into a radial portion I6, and the radial portion is formed with .openings I'l and I8, respectively provided to receive a refrigerant discharge conduit i9, and a binding post or connectorv 2l forv the wires leading to theelectric motor Il. The dome portion 22 of the shell l2 is also provided with an inlet fitting 23, through which returning refrigerant vapor is drawn into -the casing.

As bearing on the use of the compressor for refrigerating purposes, it is believed sufdcient here ,to note that in the usualcompressor type of refrigeration machine, the volatile refrigerant medium is compressed bythe compressor, then discharged into a condenser wherein it is cooled with accompanying liquefactio then admittedy to an evaporator for expansion with accompany ing absorption of heat, and is then returned to the compressor for a repetition of the cycle. As this ls all well understood, no further illustration or explanation is deemed necessary here.

The compressor casting body I0 includes a main portion 25 in which is integrally included a cylinder block 26, crankcase section 21, and mounting flange 2 8. The mounting flange is pressed into tight engagement with the inner.

wall of the cylindrical portion I5 of the upper shell l2, and the inner lsurface of the flange in turn receives the stator 29 of the motor Il, which also may be pressed fitted. The crankcase portion 21 of the body 25 includes an upper wall :il disposed laterally of the casting, in which is centrally formed a main bearing boss 32. The crankc'ase portion also includes a depending section 33, terminating in a lower horizontal Awall 34 provided with a large cylindrical opening35 which is ultimately covered with a separate lower bearing block 36. As will best appear from Fig.'2,

the depending section 33 is open to permit access to the crankcase for assembly purposes.4

`The cylinder block portion 26 projects Ifrom the left as viewed in Fig. 2, or away from the crankcase opening. This portion is formed with a horizontal bore 31 constituting the compressor cylinder, and which is capped on its head end by a valve plate 38 and overlying cylinder head 39these details being more fully illustrated in my aforesaid copending application.

The 'cylindert'l receives a reciprocatory piston 4I winch is connected through a connecting rod 42 to the crankshaft 43. The shaft,as it will now be clearly understood, is vertically mounted in .the main casting 25; in the bearings formed in the parts 32 and 36, and the upper section of the shaft projects into theA shell i2 to receive the rotor 44 of the motor Il. When the motor is excited the shaft 43 rotates, thus operating the compressor.

The motor stator 29 is provided with a longitudinal aperture in which is positioned a refrigerant inlet pipe 46 which communicates with the cylinder head 39 to admit returning vapor to the compressor. vapors entering the shell assembly, through the tting 23, flow into the compressor through the pipe 6, and excess amounts of oil returning therewith are separated and fall into the main oil body contained in the ashell I3, asindicated in Fig. l. It will be noted that the oil body has sumcient depth to cover the block I6, throughwhich oil is supplied for lubricating purposes. l

With this general explanation of the compressor assembly and operation, attention is now invited to Figs. 2 to 4, showing in greater detail the shaft construction. It will first be observed that the shaft 43 is provided with two aligned or concentric cylindrical portions 4l and 48 respectively, the upper of which receives the rotor 44, while the lowerl is mounted in the lower bear- 32, and for lubricating purposes the section 49 is formed with a spiral oil groove 5I and a retaining groove 52.

The intermediate portions of the` shaft d3, which are located within the crankcase portion, consist of a counterweight-recelvlng section 5S and an eccentric or crank section i4.' These are, respectively, contiguous with the sections 49 and '48, and they arealso contiguous with each other.

section 48 aligned therewith.

from, or eccentric to, the. concentric shaft sections 41, 49, and 48, at least in part. Thus, the

counterweight section 53 is formed with a cylindricalsurface 55 which is concentric with the axis of the shaft, and an opposed arcuate surface 58 which is concentric to the surface of the crank section 54. The section-54, necessarily, is formed with a cylindrical surface whose center is not coincident with the main shaft axis. There is accordingly provided a rotating shaft portion which lies beyond the concentric bearing sections, and which, as hereinafter more fully described, may .be utilized to pump oil to the connecting rod bearings.

Before proceeding with such description, it will be noted that thev shaft section 53 receives a oney piece counterweight 58 which is formed with a cylindrical bore 58, adapted to be disposed about the section 53, and which bore is of the same radius as that vof the-surface 55. The counterweight is also tapped to receiveset screws 8|, 62, the innermost of which engages a socket 63 formed on the shaft section 53, to secure the counterweight in its assembled position.

The piston 4I is connected to the shaft `4-3 by the connecting rod 42, thesmall end 85 of which (see Fig. 4) is connected to a wrist pin (not shown) in the usual manner. The big end 86 is formed as a strap encircling the eccentric 54; The inner surface of the strap is also formed with an oil receiving groove 81 which communicates with a duct 68 drilled through the rod 42, and leading to the small end 55. Thus, upon the provision of means for feeding oil to the groove 61, it will be apparent that lubricating oil may be supplied under pressure to both ends of the connecting rod 42, thus lubricating the eccentric and the piston wrist pin.

It will be observed that the described structure presents an interesting problem inV assembly, and the .various sections of the shaft 43 are so made and dimensioned, with respect to eachv other and the associated parts, as to solve this problem. Let it be assumed that the several parts are ready for assembly. The piston 4|, with the connecting rod attached thereto by the wrist pin connection, is inserted in the .cylinder 31. The counterweight 58 is then disposed above the strap portion 58, the crankcase opening being large enough for this purpose.

The shaft 43 is then inserted in an upward direction through the lower opening 35, and it will be observed that its concentric sections 41 and 49 passfreely through the strap and counterweight openings. These upper shaft sections then move through the main bearing 32. The counterweight section 53, of course, passes freely through the strap 88; but as it comes up to the counterweight bore 59, it is necessary to offset the counterweight with respect ,to the shaft. and this can be done because the bore 59 has a diameter the same as the oil'set cylindrical surface 55. while the arcuate surface 58 lies within the trace of the concentric sections. At the same time, the connecting rod may be moved back and forth inthe cylinder block, thus permitting the strap 88 to encircle the eccentric portion 54. Upon tightening up the set screws 5| and 52, the parts just described are brought into' assembled relation, as shown in Figs. 2 and 4. The shaft 43. is then located in the bearing 32,- with its lower The lower section 48 is mounted in thebearing block 38, which is formed with a centering ing 35,-and which is secured to the main body 25 by screws 12. The central portion of the block 38 is formed with a bearing boss 13 which is open at its lower end, and within which the lower shaft section 48 is supported. Disposed over the lower end of the boss 13 is a thrust bearing plate 14 which is secured tothe block. 38 by screws 15 (see Fig. l). 'I'he plate 14 is also provided with a central opening 18 to admit oil from the main oil body to the lower end of the shaft 43.

The lower end of the shaft 43, and in the section 48, is drilled for a limited distance with an axially disposed bore 11, which constitutes the eye of a centrifugal pump, and which is aligned with the opening 16. The section 43 is also drilled with two radial passages 18 and 19 which communicate with the eye 11. The shaft section 43 is then drilled with vertical passages 8| and 82, which are offset from but parallel to the main shaft axis, and which respectively intersect the radial passages or vanes 18 and 19. It will be noted that the passage 8| continues to a point substantially half way up the eccentric section 54, while the passage82 continues up through the eccentric and counterweight sections to terl minate adjacent the lower part of the bearing section 49. Each of these vertical passages constitutes a riser, or discharge pipe, for its associated centrifugal pump formed by the vanes 18 and 19.

It will be noted, however, that since the passages 8| and 82 are vertically disposed and are parallel to the shaft axis, there is no point therein more remote from the center of rotation than any other point, and accordingly there is no horizontal componentithroug'h which centrifugal force may be developed. On the other hand, the passages 18 and 19 lie Iwholly in a plane perpendicular to the axis of rotation, and therefore every point therein is effective as a centrifugal pump during rotation, but not as a riser or discharge pipe subjecting such passage to a pressure head. The centrifugal pumps are, therefore, constantly vsubmerged and accordingly constantly primed, and are not susceptible of binding or blocking by gas formations, since the oil body itself places the eye 11 under some measure of positive pressure, rather than a negative suction pressure.

Accordingly, upon rotation of the shaft 43, the passages 18 and 19 form centrifugal impellers, drawing oil from the main body and discharging it into the risers 8| and 82, wherein, due to the absence of a centrifugal component, the whole available kinetic head of the pump is converted into pressure head. It is interesting to note that, while these impellers are very small,

as compared to the dimensions of the usual centrifugal pump, it has nevertheless been demonstrated that they develop adequate energy to pump the oil, under the speeds of rotation employed in compressors of this nature.

It is moreover quite apparent that the oil discharged from the vanes 18 and 19 would not beeil'ectively elevated in the risers 8| and 82. if the open ends` of the vanes, and the lower ends of the risers, were not covered; Rather than put plugs in -these openings, which would add to the expense of manufacture. the open ends are utilized to advantage, by covering them with the bearings 13 and 14. Thus, the openends of the vanes 18 and 19 communicate with the inner surface of the radial bearing 13, to supply a flange 1| engaging the inner surface of the tpen'- v limited amount of oil thereto as needed, While the lower ends of the risers 8l and 82 are covassurance is provided thereby against failure of lubrication.

The riser 82 terminates in a lateral opening 83- drilled in the main bearing section 48, and thus supplies oil to the bearing 32, for distribution by the groove 5I. The circumferential groove 52 retains some oil for return by gravity as required, and hence the main bearing is adequately lubricated at all times.

The riser 8|, however, terminates in a radial duct 84 which is drilled through the offset section of the eccentric 54, and oil supplied through the riser 8| may therefore be discharged into the groove 61, both to lubricate the strap bearing, and also for discharge through the duct 68 to 4supply oil to the small end 65 of the connecting rod. From what has been stated with respect to the development of centrifugal force, it is ajpparent that the duct 84, being disposed in a plane normal to the axis of rotation, in itself constitutes a centrifugal pump. Thus, by providing two radial portions, and a connecting vertical portion, there is formed in effect a two stage centrifugal pump, whose capacity is much greater than that; of a single pump.

I do not wish to be too strictl limited by this explanation of the principle, b cause the structure obviously possesses certain differences from the usual multi-stage centrifugal. It is apparent, however, that the lower submerged pump 18 discharges its effluent to the inlet of a second pump 84, and the second pump dischargesits eliluent with greater force. It may be otherwise said that the first centrifugal acts as a priming pump for the second centrifugal, since the vane 84 is located above the oil body, and therefore is not self-priming. In any event, observation shows that a greatly increased pumping action is obtained, and adequate quantities of oil are Asupplied to the eccentric and wrist pin, and to the cylinder walls. l

.In the embodiment of the invention just .described, the risers areformed in the shaft itself, and it may be deemed expedient to replace the 'riser for the bearing 32 with an exterior riser. In such event, the structure shown in Fig. 5 may be utilized. As the general arrangement of parts is the same, these are designated,

by like reference numerals with the suilix a, and without repetition of description.

The crankcase portion of the main body a is formed with a depending portion 33a, which is vertically drilled with a riser duct 86, an upper discharge duct 8l communicating with the bearing 32a, and a lower lateral duct 88 communicating withthe outer flanged surface of the bearing block 38a. The block, in turn, is drilled with a passage 89 to connect the riser 86 with the discharge opening of the vane 18a .formed in the shaft 48a. As the shaft rotates, the oil is driven by the centrifugal pump through the stationary riser and duct system,to supply oil under pressureu to the overhead bearing.

From the foregoing description, it will be seen that this invention resides in a hermetic compressor of the overhead motor type, wherein the cooperative parts have been so devised as to force the lubricant in the lower shell under pressureto the bearings, and wherein a totally submerged and constantly primed centrifugal pump is utilized to develop the initial pressure on the soY vGU

oil. It will be seen that the provision of the pump and riser structure is effected in conjunction with a main shaft whose various sections are correlated to the functions of supplying oil and operating the parts of the compressor, and.

that a lower bearing `structure is provided in such fashion as also to constitute a part of the pump, as well as the general assembly.

My invention resides in these related parts co operating to produce an improved and less ex-y pensive compressor, and while I have describedv the invention with reference to specific embodiments thereof, it will be understood that it is not intended to be strictly limited thereto, but is intended to embrace those modifications and variations which are within the scope of the ,combinations and parts'set forth in the following claims.

I claim:

said motor and compressor, one of said bearings l being disposed adjacent the motor and the other of said vbearings being disposed below the compressor and adjacent the lower portion of the shell, said lower shell portion being adapted to receive an oil body immersing at least a portion of said lower bearing, a main shaft having concentric portions radially mounted in both of said bearings, said shaft having a concentric portion extending above said upper bearing for connection to said motor, an eccentric portion formed on said shaft intermediate said bearings, a connetting rod for said compressor connected to said eccentric portion, a horizontally disposed radial passage formed in said lower concentric shaft portion and having open communication with the wall of said lower bearing at its outer end and with the shaft axis at its inner "end, an axial passage in the lower end of the shaft communicating with the radial passage thereby to admit oil to said radial passage for centrifugal pumping, and a vertical passage drilled through -said shaft in spaced relation to said axis and parallel thereto, said vertical passage extending from said radial passage through said eccentric portion to said upper bearing portion. c

2. The hermetic/compressor of claim l, wherein said vertical passage is open to the lower end of `said shaft, and wherein a thrust bearing is sevcured to said lower radial bearing to abut the end of said shaft and to coverthe lower open end of said passage.

3. A hermetic compressor comprising a casting body formed with a mounting flange portion and a compressor portion, a shell enclosing the body and supporting said casting body, a motor mounted within the flange portion, said casting body being'formed with 'an assembly and bearing block -operatively connecting the shaft to the rcompressor portion, a bearin-g block adapted to be secured to said body portion to close said opening, said block having a'lower radial bearing aligned with said first named bearing, a thrust plate se-l 1. A hermetic compressor comprising a shell, a A

cured to said block and covering the end of the shaft disposed in said lower bearing, an axially alignedv opening formed in said thrust plate, an axial bore formed in the lower end of the shaft and extending thereinto a limited distance, a laterally disposed duct drilled in said shaft normal to the axis thereof from the surface of said shaft to saidv axiall bore, said duct being open at its outer end and wholly disposed within the surface of said lower bearing, said shell being adapted to contain oil to adepth sufficient to submerge said thrust plate with the eccentric shaft portion above said oil, and riser ducts 'communicatingvwith said rst duct and with said upper bearing,'said first duct being blocked from recirculation of oil to said body directly by said lower bearing and thrust plate.

4. In a refrigerant compressor of the type described, a compressor body having upper and lower bearings, a crankshaft rotatably carried by the ing and comprising an open axial hole in the lower end of the shaft constituting the eye of the impeller, a communicating radial hole constituting an impeller arm whose outer end is closed by the lower bearing, a longitudinal hole in the shaft communicating with said arm and extending upward, a bearing lubricating port communicating with said longitudinal hole, and means connecting said impeller eye with the oil reservoir comprising a hole formed in said thrust bearing aligned with said impeller.

J ENS TOUBORG. 

